Entomol. Mitt. Zool. Mus. Hamburg 15 (186): 335-359 Hamburg, 1. Dezember 2011 ISSN 0044-5223 Bergtrollus dzimbowski gen. n., sp. n., a remarkable new tardigrade genus and species from the nival zone of the Lyngen Alps, Norway (Tardigrada: Milnesiidae) HIERONYMUS DASTYCH (with 51 gures) Abstract Bergtrollus dzimbowski gen. n., sp. n., a new genus and species of Tardigrada (the Milnesiidae) from moss in the nival zone of the Lyngen Alps (Norway), is described. This is the second milnesiid genus, apart from Milnesium Doyère, 1840, known to oc- cur in the Northern Hemisphere. The new tardigrade is characterized by a strikingly long and protrusible proboscis (‘snout’) formed by the prolonged mouth region. A simi- lar organ in Eutardigrada has also been reported in Milnesioides exsertum Claxton, 1999 and in the recently discovered Limmenius porcellus Horning et al., 1978 (see Claxton 1999) (both Milnesiidae). These species are known from limited records in New Zealand and Australia. The shape and length of the buccal tube in Bergtrollus gen. n. is intermediate between those of Milnesioides and Limmenius, but the mouth cavity is similar to Milnesium. Diagnostic morphological characters and identi cation key for all four genera of the Milnesiidae are presented and the phylogenetic status of the new taxon within the family is discussed. Keywords: Tardigrada, taxonomy, Bergtrollus dzimbowski gen. n., sp. n., nival zone, the Lyngen Alps, Norway, the Arctic. Introduction Milnesium tardigradum Doyère, 1840 is one of the rst described, still valid, worldwide recorded and commonly known tardigrades. The species repre- sents well-separated phyletic branch within Eutardigrada de ned by Schuster et al. (1980) as the order Apochela. The order consists of the sole fam- ily Milnesiidae Ramazzotti, 1962 with the three genera, Milnesium Doyère, 1840, Limmenius Horning et al., 1978 and Milnesioides Claxton, 1990. Within Milnesium more than 16 nominal species have been described in recent years (for a check-list see e.g., Guidetti & Bertolani 2005, Degma & Guidetti 2007). Two remaining genera are monospeci c and represented by Limmenius porcellus Horning, Schuster & Grigarick, 1978 and Milnesioides exsertum Claxton, 1999. These species, in particular L. porcellus, are char- acterized by a very long buccal tube, as compared to Milnesium. Moreover, 14674 - Entomologische Mitteilungen - Band 15 - Nummer 186.pdf 31 13.12.2011 09:05:32 336 DASTYCH, H. Figs 1-2. The type locality of Bergtrollus dzimbowski gen. n., sp. n.: general (1) and detailed (2) view. In the background E slope of the subsummit of Mt. Steindalstinden. 14674 - Entomologische Mitteilungen - Band 15 - Nummer 186.pdf 32 13.12.2011 09:05:32 Bergtrollus dzimbowski gen. n., sp. n. 337 the uppermost part of the head and mouth region in M. exsertum form a characteristic, extremely long ‘snout’ (Claxton 1999), a structure not known in other Eutardigrades. The presence of the snout (= proboscis) has also been discovered recently in the originally poorly described Limmenius (see Claxton, l.c.). While the members of Milnesium are common and distributed worldwide, those of Limmenius and Milnesioides have been recorded very rarely and only from the Southern Hemisphere. L. porcellus is known from a few localities in New Zealand (Horning et al. 1978) and from a single speci- men from Tasmania (Claxton 1999), while M. exsertum has been reported only from Australia, including Tasmania (Claxton, l.c.). When recently processing bryophytes from the Lyngen Alps (Northern Norway), several milnesiid tardigrades intermediate in their morphology be- tween Limmenius and Milnesioides were encountered. Analysis of the ma- terial brought to light a new and remarkable tardigrade genus and species and also the rst record of the second genus of the family Milnesiidae in the Northern Hemisphere. The paper describes the new tardigrade, compares it with other milnesiid genera and discusses its phylogenetic status within the family. Furthermore, a diagnostic key for these genera is provided. Material and Methods The new tardigrade were found in a small sample of moss (ca 7-10 cm2) collected in the nival zone of the Lyngen Alps, Norway (for details see “type locality” below). The moss was placed in a paper bag and air-dried. After seven months the sample was soaked in distilled water and kept overnight at the temperature of 0 °C. Tardigrades were extracted by the method described by Dastych (1985), with some living individu- als being observed under a stereo-microscope. The animals were [ xed for SEM ex- amination with hot Bouin’s medium, dehydrated, critical-point-dried and carbon-coated or, for light microscope study, killed with hot water and mounted in a Faure’s medium as permanent microslide preparations. One specimen (holotype) was xed in a mix- ture of methanol and acetic acid (3:1), stained with aceto-lactic orcein (see e.g. Berto- lani 1971) and mounted after examination, like other specimens, in Faure’s medium. Measurements were taken with PHC. The body length was measured without legs IV, mostly with retracted proboscis (‘snout’). The proboscis was fully extended in only two preserved individuals (one mounted for SEM: Figs 3, 11). However, as these ani- mals represent simplex-stage, their lamellar operculum and peribuccal papillae are torn away (Figs 15-17). Consequently, the proboscis was measured without these structures (slide no. 1982A, Table 1, column “b”: 80.1 m). The length of the organ, when available, was obtained indirectly from the remaining individuals (n = 3, holotype included), i.e. through adding lengths of retracted pseudosegments of the proboscis and that of lamellar operculum. The distance between the (upper) edge of the base of the cephalic papilla and the apex of the mouth region was considered as the length of the snout. The length of the bucco-pharyngeal and buccal apparatus includes peribuccal la- mellae. The term ‘buccal apparatus’ includes mouth cavity, buccal tube and associated structures; the ’bucco-pharyngeal apparatus’ embraces additionally the pharynx. The mouth cavity (= ‘mouth ring’ by Dewel & Clark 1973, in part) was measured with and 14674 - Entomologische Mitteilungen - Band 15 - Nummer 186.pdf 33 13.12.2011 09:05:33 338 DASTYCH, H. 14674 - Entomologische Mitteilungen - Band 15 - Nummer 186.pdf 34 13.12.2011 09:05:33 Bergtrollus dzimbowski gen. n., sp. n. 339 without the lamellae. The (external) diameter of the mouth cavity was taken at the bases of the peribuccal lamellae, immediately below their perpendicular striation. The mouth cavity length (that without lamellae) is the distance between the upper (strongly sclerotized) edge of the stylet sheaths and the level of the bases of peribuccal lamel- lae, just below their striation (comp. Claxton 1999). The length of the buccal tube was measured from the upper edge of the stylet sheaths up to the posterior edge of the tube, including terminal apophyses. The length of the buccal tube is made up of two units, i.e. that from the upper edge of the stylet sheaths up to the anterior edge of the stylet support insertion (= SSA unit; = pt ss index in Tumanov 2006, based on Pilato 1981) and that from the anterior (fore) edge of the stylet support insertion up to the posterior edge of the tube, including its terminal apophyses (= SSB unit). The (external) diameter of the tube is taken just above the insertion of the stylet supports. Two specimens (slide no. T1985c and T1982d) had on the left and right side of the tube different (aberrant) length of the unit SSB. The unit sides measured 58.3 vs. 63.0 and 61.1 vs. 64.8 m, respectively. Arbitrarily, the higher values of these lengths have been considered for calculations. The whole length of the primary (= main) branch of the claw was measured from the apex of accessory spines up to the external edge of the arch-like cuticular bar (mbb: Figs 30, 31), which bar is located dorsally and laterally at the nger-like base of the branch. The length of sclerotized unit of the primary branch was measured from the apex of accessory spines up to very proximal termination of its sclerotized com- ponent (= “main branch length” in Tumanov 2006: Fig. 1). The length (height) of the remaining (i.e. basal) part of claw (= ‘basal claw’: Fig. 29: bc) includes lunula (= ‘basal thickening’: e.g. Tumanov 2006) and is the distance between the tip of the secondary branch and the posterior edge of the lunula. An additional measurement of the basal claw excludes the lunula. The width of lunula is a diameter of the structure. The morphometric indices applied are de ned in Dastych (2006, 2011). For calcu- lation of the hind claw base index (“HBI”) only the sclerotized part of the claw main branch was considered [the length (height) of hind basal claw, lunula excluded x 100 / sclerotized unit of the hind claw main branch]. Furthermore, the following new mor- phometric indices have been introduced: 1) the snout / body index (“SBI”) i.e., the (percent) ratio between the length of the snout (proboscis) and the body; 2) the mouth cavity index (“MCAVI”) which describes the shape of the mouth cav- ity [the length of mouth cavity, peribuccal lamellae excluded x 100 / mouth cavity width]; 3) the hind claw lunula index (“HLI”) which de ned the size of the hind lunula (the hind claw lunula width x 100 / the basal claw length, lunula included). Microphotographs were taken with ZEISS ‘Fotomikroskop III’, SEM micrographs with LEO 1525. Figures 19, 23, 24, 34 come from the holotype of the new taxon, the other images represent paratypes. Figs 3-6. Bergtrollus dzimbowski gen. n., sp. n., animal in simplex-stage. 3. habitus: latero-dorsally, 4-6: apex of the proboscis (‘snout’) in latero-dorsal, latero-ventral and lateral view, respectively (peribucal lamellae and papillae torn out).